Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON3):

Solution:
H,W=map(int,input().split())
MAP=[["#"]*(W+2)] + [["#"]+list(input())+["#"] for i in range(H)] + [["#"]*(W+2)]
white=0
for line in MAP:
    white+=line.count('.')
from collections import deque
check=deque([(1,1,1)])
dist=float('inf')
while len(check)>0:
    d,x,y=check.popleft()
    for i,j in [(-1,0),(1,0),(0,1),(0,-1)]:
        if MAP[x+i][y+j]==".":
            if x+i==H and y+j==W:
                dist=d+1
                check=[]
                break
            check.append((d+1,x+i,y+j))
            MAP[x+i][y+j]="#"
if dist>10**10:
    print(-1)
else:
    print(white-dist)